Derivatives of Borole, XVI1),—Bis(borole)nickel Complexes2)The dilithium 1‐(dialkylamino)dihydroborolediides Li2[C4H4‐BNR2]2a, b: R = Me, Et) react with NiCl2· DME to give bis(borole)nickel complexes Ni(C4H4BNR2)2. Nucleophilic substitution reactions are used to produce a large variety of derivatives Ni(C4H4BR)21(e.g. R = H,tBu, F, Cl, Br, I, OH, OMe). Treatment of Ni(C4H4BCl)2(tg) with LiO(CH2)3OLi in THF produces a polymer and a dinuclear complex (μ‐{η5:η5‐[(CH2)3(OBC4H4)2]}2Ni2(3) which crystallizes from CH2Cl2as solvate3· CH2Cl2. The complexes1gand3· CH2Cl2are characterized by X‐ray diffraction work. Barriers to internal ring‐ring rotation are measured by variable‐temperature NMR spectroscopy. The B—H bond of Ni(C4H4BH)2(1a) is remarkably inert and does not react with H2O or with carboxylic acids in THF at room temperature. With PhCHO slow formation of the benzyloxy compound Ni(C4H4BOCH2Ph)2(1 m) is observed at 100°C. For typical complexes such as the phenyl derivative1ecyclic voltammetry in CH2Cl2reveals an irreversible oxidation at 1.32 and a quasi‐reversible re